CN114990423A - A kind of production method of strong toughness hot work die steel - Google Patents

Abstract

The invention discloses a production method of strong-toughness hot-working die steel, and particularly relates to the field of alloy manufacturing, wherein the production method comprises the steps of S1, smelting and filtering; s2, vacuum treatment; s3, homogenizing at high temperature; s4, forging; s5, performing stage heat treatment; s6, staged cold treatment; and S7, nitriding to finally obtain the hot-work die steel. The invention improves the solid solution capacity of Co-Ni as a substrate by converting the traditional Co substrate into an innovative idea of taking Co-Ni as a substrate and the characteristic of infinite mutual solubility of Co-Ni, plays a role of multi-alloying, leads the interior of the Co-Ni to generate a Y phase with high structure and high stability, leads the outer layer of the Y phase to generate a nitride compound layer of gamma phase or epsilon phase and other phases during nitriding treatment, eliminates the nitride compound layer of epsilon phase and other phases through second nitriding treatment, only keeps the Y phase, obtains the Y phase on the basis of NbCrN phase, leads the interior of the prepared die steel to be uniformly distributed with high-density nano strengthening phases, thereby improving the high temperature resistance and the corrosion resistance of the die steel.

Description

A kind of production method of strong toughness hot work die steel

technical field

The present invention relates to the technical field of alloy manufacturing, and more particularly, to a method for producing strong and tough hot work die steel.

Background technique

Mould is known as the "mother of modern industry", which shows the importance and indelible contribution of tooling and moulding in modern industry. Among them, mould steel is the most important part of moulding and the most widely used material in moulding materials. The important material carrier and technical foundation of the mold manufacturing industry, its variety, specification and quality play a decisive role in the performance, service life and manufacturing cycle of the mold. Steel is an extremely important metal material in economic construction. According to the chemical composition, it is divided into two categories: carbon steel (referred to as carbon steel) and alloy steel. Carbon steel is an alloy obtained by smelting pig iron. In addition to iron and carbon as its main components, it also contains a small amount of manganese, silicon, and impurities such as sulfur and phosphorus. Carbon steel has certain mechanical properties, good process performance and low price. Therefore, carbon steel has been widely used. However, with the rapid development of modern industry and science and technology, the performance of carbon steel can not fully meet the needs, so people have developed various alloy steels. Alloy steel is a multi-component alloy obtained by purposefully adding certain elements (called alloying elements) on the basis of carbon steel. Compared with carbon steel, the performance of alloy steel has been significantly improved, so it is widely used.

In the production of general alloy steel, on the basis of TP310 austenitic heat-resistant steel, the carbon content is limited, and the strong carbonitride forming element niobium with a mass fraction of 0.20% to 0.60% and a mass fraction of 0.15 are added. % ~ 0.35% nitrogen, using precipitation dispersion distribution, fine NbCrN phase and Nb-rich carbonitride and M23C6 (M is Cr and metal elements that can replace Cr, such as Fe) type carbides for strengthening to obtain nano-strengthening However, the general production phase is single, and the particle diameter is large and the number is small, so it is necessary to change its composition and study its suitable production process to increase the number of strengthening phases and obtain different phases. phase diameter to obtain high-density nano-strengthened phases.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a method for producing strong and tough hot work die steel. The technical problem to be solved by the present invention is: increasing the number of strengthening phases and obtaining different phases, reducing the diameter to obtain high-density nano-strengthened phases.

In order to achieve the above purpose, the present invention provides the following technical solutions: a strong and tough hot work die steel, wherein the main materials used in the die steel include the following raw materials by weight: carbon C: 0.20-0.30%, silicon Si: 0.20-0.40 %, Manganese Mn: 0.40～0.6%, Molybdenum Mo: 1.50～2.20%, Nickel Ni: 0.50～0.80%, Niobium Nb: 0.50～0.60%, Cobalt Co: 0.50～0.60%, Chromium Cr: 5.00～5.40%, Yttrium Y: 0.01～0.03%, Vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities sulfur S≤0.006%, phosphorus P≤0.018%.

The invention provides a production method of strong and tough hot work die steel, comprising the following operation steps:

S1. Smelting and filtration: heating the raw materials to above 1500°C in a smelting furnace and smelting into molten steel, pouring the prepared molten steel into a filtration furnace to remove excess phosphorus, sulfur and other impurities;

S2, vacuum treatment: inert gas is sprayed into the reduction furnace, and the molten material can be stirred during the blowing process;

S3. High temperature homogenization: heat the cooled steel billet to 1100°C, and after holding for a predetermined time, cool to 150°C for the first homogenization to obtain a primary homogeneous steel ingot, and heat it again to 1260°C-1300°C for homogenization. Quality 5 to 8 hours;

S4. Forging: The three-pier three-pulling deformation process is used to forge the steel billet in three directions of X-axis, Y-axis, Z-axis, and the initial forging temperature is set at 1100 ° C ~ 1150 ° C, and the final forging temperature is 900 ° C. After heating, keep warm 1-2 hours to take out forging, when the temperature drops to 900 ℃, return to the furnace to heat to the initial forging temperature and then cycle forging again;

S5. Staged heat treatment:

In the first stage, the forging after high temperature diffusion is heated to 500°C to 650°C at a heating rate of 10°C to 15°C/min, kept for 1 to 2 hours, and then water-cooled to room temperature;

In the second stage, the forging after high temperature diffusion is raised to 850°C to 880°C at a heating rate of 7°C to 12°C/min, kept for 2 to 3 hours, and then water-cooled to room temperature;

In the third stage, the forgings after high temperature diffusion are heated to 1020°C to 1050°C three times at a heating rate of 5°C to 8°C/min, and kept for 20-25 hours;

S6. Staged cold treatment:

In the pre-cooling stage, pressurize the furnace so that the pressure value is maintained at 5-8 bar, and cool the heat-treated forgings to 820-900 ℃ with the furnace, and keep the temperature for 2 hours;

In the initial cooling stage, the heat-treated forgings are cooled to 400-450 ℃ with the furnace, the pressure in the furnace is released, and after holding for 2 hours, air-cooled to room temperature;

In the cryogenic stage, the heat-treated forgings are cooled to -120 to -90 °C, maintained for 2 hours, and then air-cooled to room temperature;

S7, nitriding treatment:

In the initial nitriding treatment, the cold-treated forgings are heated to 800 ℃ ~ 900 ℃ with the furnace, and the gas in the furnace is formed convection through the stirring device. Carry out in gas atmosphere, and introduce unsaturated hydrocarbon gas and ammonia gas at the same time;

In the second nitriding treatment, in the second nitriding treatment process, the temperature in the furnace is lowered to 500 ° C ~ 600 ° C, and ammonia gas and hydrogen gas are introduced into the heating chamber, so that the nitrogen potential becomes 0.16 ~ 0.25, and the nitrogen potential becomes 0.16 ~ 0.25. In the atmosphere, keep for 2 to 4 hours, and air-cool to room temperature.

In a preferred embodiment, in the step S3, the steel billet is heated to 1100° C., and after holding for a predetermined time, and then cooled to 175° C., when the effective thickness of the steel billet is greater than 350 mm, the cooled The speed is: 8-10°C/min; when the effective thickness of the steel billet is less than 350 mm, the cooling speed is: 10-20°C/min.

In a preferred embodiment, in the staged heat treatment process in step S5, water cooling to room temperature can be selected from oil cooling to room temperature or air cooling to room temperature.

In a preferred embodiment, in the step S6, the interval time for the intermittent introduction of the unsaturated hydrocarbon gas and the ammonia gas is 2 min to 6 min, and the flow rate of each time the unsaturated hydrocarbon gas and the ammonia gas is introduced is (0.35 ~0.65) m3/h.

In a preferred embodiment, the used main material includes the following raw materials by weight: carbon C: 0.20%, silicon Si: 0.20%, manganese Mn: 0.45%, molybdenum Mo: 2.00%, nickel Ni: 0.50 %, Niobium Nb: 0.55%, Cobalt Co: 0.50%, Chromium Cr: 5.00%, Yttrium Y: 0.01%, Vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and unavoidable Pure sulfur S≤0.006%, phosphorus P≤0.01%.

In a preferred embodiment, the used main material includes the following raw materials by weight: carbon C: 0.25%, silicon Si: 0.30%, manganese Mn: 0.50%, molybdenum Mo: 1.90%, nickel Ni: 0.65 %, Niobium Nb: 0.55%, Cobalt Co: 0.55%, Chromium Cr: 5.20%, Yttrium Y: 0.023%, Vanadium V: 0.55%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities Sulfur S≤0.006%, phosphorus P≤0.01%.

In a preferred embodiment, the used main material includes the following raw materials by weight: carbon C0.30%, silicon Si: 0.40%, manganese Mn: 0.6%, molybdenum Mo: 2.20%, nickel Ni: 0.80 %, Niobium Nb: 0.60%, Cobalt Co: 0.60%, Chromium Cr: 5.40%, Yttrium Y: 0.03%, Vanadium V: 0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities Sulfur S≤0.006%, phosphorus P≤0.01%.

Technical effects and advantages of the present invention:

1. The present invention creates dynamic conditions that are favorable for the diffusion of carbon and alloy elements through two homogenization and different cooling methods, and three-axis forging alternately. The liquefied carbides in the billet and the band-like structure due to dendritic segregation make it obtain better toughness, ductility and isotropy, staged heat treatment and staged cold treatment, so that the thermal stress spreads better and more uniformly , while meeting the hardness requirements of die steel while taking into account its toughness and stability.

2. The present invention improves the solid solution ability of Co-Ni as the matrix by transforming the traditional Co matrix solid solution into the innovative idea of using Co-Ni as the matrix, and the feature of infinite mutual solubility of Co-Ni, and exerts the effect of multi-alloying , to form a high-structure and high-stability Y-phase inside, and to form a nitride compound layer of γ-phase or ε-phase and other phases in the outer layer during nitriding treatment, and remove the ε-phase and other phases through the second nitriding treatment. The nitride compound layer of other phases retains the Y phase, and obtains the Y phase on the basis of the NbCrN phase, so that the high-density nano-strengthened phase is evenly distributed in the prepared die steel, thereby improving its high temperature resistance and corrosion resistance.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

The invention provides a strong and tough hot work die steel, wherein the main materials used in the die steel include the following raw materials by weight: carbon C: 0.20-0.30%, silicon Si: 0.20-0.40%, manganese Mn: 0.40-0.6 %, Molybdenum Mo: 1.50～2.20%, Nickel Ni: 0.50～0.80%, Niobium Nb: 0.50～0.60%, Cobalt Co: 0.50～0.60%, Chromium Cr: 5.00～5.40%, Yttrium Y: 0.01～0.03%, Vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities sulfur S≤0.006%, phosphorus P≤0.018%.

Specifically in this embodiment, the main materials used in the die steel include the following raw materials by weight: carbon C: 0.20%, silicon Si: 0.20%, manganese Mn: 0.45%, molybdenum Mo: 2.00%, nickel Ni: 0.50%, Niobium Nb: 0.55%, Cobalt Co: 0.50%, Chromium Cr: 5.00%, Yttrium Y: 0.01%, Vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and unavoidable Impurity sulfur S≤0.006%, phosphorus P≤0.01%. The present invention provides a production method of strong and tough hot work die steel, comprising the following operation steps:

S1. Smelting and filtration: heating the raw materials to above 1500°C in a smelting furnace and smelting into molten steel, pouring the prepared molten steel into a filtration furnace to remove excess phosphorus, sulfur and other impurities;

S2, vacuum treatment: inert gas is sprayed into the reduction furnace, and the molten material can be stirred during the blowing process;

S3. High temperature homogenization: heat the cooled steel billet to 1100°C, and after holding for a predetermined time, cool to 150°C for the first homogenization to obtain a primary homogeneous steel ingot, and heat it again to 1260°C-1300°C for homogenization. Quality 5 to 8 hours;

S4. Forging: The three-pier three-pulling deformation process is used to forge the steel billet in three directions of X-axis, Y-axis, Z-axis, and the initial forging temperature is set at 1100 ° C ~ 1150 ° C, and the final forging temperature is 900 ° C. After heating, keep warm 1-2 hours to take out forging, when the temperature drops to 900 ℃, return to the furnace to heat to the initial forging temperature and then cycle forging again;

S5. Staged heat treatment:

In the first stage, the forging after high temperature diffusion is heated to 500°C to 650°C at a heating rate of 10°C to 15°C/min, kept for 1 to 2 hours, and then water-cooled to room temperature;

In the second stage, the forging after high temperature diffusion is raised to 850°C to 880°C at a heating rate of 7°C to 12°C/min, kept for 2 to 3 hours, and then water-cooled to room temperature;

In the third stage, the forgings after high temperature diffusion are heated to 1020°C to 1050°C three times at a heating rate of 5°C to 8°C/min, and kept for 20-25 hours;

S6. Staged cold treatment:

In the pre-cooling stage, pressurize the furnace so that the pressure value is maintained at 5-8 bar, and cool the heat-treated forgings to 820-900 ℃ with the furnace, and keep the temperature for 2 hours;

In the initial cooling stage, the heat-treated forgings are cooled to 400-450 ℃ with the furnace, the pressure in the furnace is released, and after holding for 2 hours, air-cooled to room temperature;

In the cryogenic stage, the heat-treated forgings are cooled to -120 to -90 °C, maintained for 2 hours, and then air-cooled to room temperature;

S7, nitriding treatment:

In the initial nitriding treatment, the cold-treated forgings are heated to 800 ℃ ~ 900 ℃ with the furnace, and the gas in the furnace is formed convection through the stirring device. Carry out in gas atmosphere, and introduce unsaturated hydrocarbon gas and ammonia gas at the same time;

In the second nitriding treatment, in the second nitriding treatment process, the temperature in the furnace is lowered to 500 ° C ~ 600 ° C, and ammonia gas and hydrogen gas are introduced into the heating chamber, so that the nitrogen potential becomes 0.16 ~ 0.25, and the nitrogen potential becomes 0.16 ~ 0.25. In the atmosphere, keep for 2 to 4 hours, and air-cool to room temperature.

In the step S3, the steel billet is heated to 1100°C, and after holding for a predetermined time, and then cooled to 175°C, when the effective thickness of the steel billet is greater than 350 mm, the cooling rate is: 8-10°C /min; when the effective thickness of the steel billet is less than 350 mm, the cooling speed is: 10-20 ° C / min, in the step S5 in the staged heat treatment process, water cooling to room temperature can choose oil Cool to room temperature or air-cool to room temperature, in the step S6, the interval time of introducing unsaturated hydrocarbon gas and ammonia gas intermittently is 2min～6min, and the flow rate of importing unsaturated hydrocarbon gas and ammonia gas is ( 0.35～0.65)m3/h.

Example 2:

The invention provides a strong and tough hot work die steel, wherein the main materials used in the die steel include the following raw materials by weight: carbon C: 0.20-0.30%, silicon Si: 0.20-0.40%, manganese Mn: 0.40-0.6 %, Molybdenum Mo: 1.50～2.20%, Nickel Ni: 0.50～0.80%, Niobium Nb: 0.50～0.60%, Cobalt Co: 0.50～0.60%, Chromium Cr: 5.00～5.40%, Yttrium Y: 0.01～0.03%, Vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities sulfur S≤0.006%, phosphorus P≤0.018%.

Specifically in this embodiment, the main materials used in the die steel include the following raw materials by weight: carbon C: 0.25%, silicon Si: 0.30%, manganese Mn: 0.50%, molybdenum Mo: 1.90%, nickel Ni: 0.65%, Niobium Nb: 0.55%, Cobalt Co: 0.55%, Chromium Cr: 5.20%, Yttrium Y: 0.023%, Vanadium V: 0.55%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities Sulfur S≤0.006%, phosphorus P≤0.01%.

The invention provides a production method of strong and tough hot work die steel, comprising the following operation steps:

S1. Smelting and filtration: heating the raw materials to above 1500°C in a smelting furnace and smelting into molten steel, pouring the prepared molten steel into a filtration furnace to remove excess phosphorus, sulfur and other impurities;

S2, vacuum treatment: inert gas is sprayed into the reduction furnace, and the molten material can be stirred during the blowing process;

S3. High temperature homogenization: heat the cooled steel billet to 1100°C, and after holding for a predetermined time, cool to 150°C for the first homogenization to obtain a primary homogeneous steel ingot, and heat it again to 1260°C-1300°C for homogenization. Quality 5 to 8 hours;

S4. Forging: The three-pier three-pulling deformation process is used to forge the steel billet in three directions of X-axis, Y-axis, Z-axis, and the initial forging temperature is set at 1100 ° C ~ 1150 ° C, and the final forging temperature is 900 ° C. After heating, keep warm 1-2 hours to take out forging, when the temperature drops to 900 ℃, return to the furnace to heat to the initial forging temperature and then cycle forging again;

S5. Staged heat treatment:

In the first stage, the forging after high temperature diffusion is heated to 500°C to 650°C at a heating rate of 10°C to 15°C/min, kept for 1 to 2 hours, and then water-cooled to room temperature;

In the second stage, the forging after high temperature diffusion is raised to 850°C to 880°C at a heating rate of 7°C to 12°C/min, kept for 2 to 3 hours, and then water-cooled to room temperature;

In the third stage, the forgings after high temperature diffusion are heated to 1020°C to 1050°C three times at a heating rate of 5°C to 8°C/min, and kept for 20-25 hours;

S6. Staged cold treatment:

In the pre-cooling stage, pressurize the furnace so that the pressure value is maintained at 5-8 bar, and cool the heat-treated forgings to 820-900 ℃ with the furnace, and keep the temperature for 2 hours;

In the initial cooling stage, the heat-treated forgings are cooled to 400-450 ℃ with the furnace, the pressure in the furnace is released, and after holding for 2 hours, air-cooled to room temperature;

In the cryogenic stage, the heat-treated forgings are cooled to -120 to -90 °C, maintained for 2 hours, and then air-cooled to room temperature;

S7, nitriding treatment:

In the initial nitriding treatment, the cold-treated forgings are heated to 800 ℃ ~ 900 ℃ with the furnace, and the gas in the furnace is formed convection through the stirring device. Carry out in gas atmosphere, and introduce unsaturated hydrocarbon gas and ammonia gas at the same time;

In the second nitriding treatment, in the second nitriding treatment process, the temperature in the furnace is lowered to 500 ° C ~ 600 ° C, and ammonia gas and hydrogen gas are introduced into the heating chamber, so that the nitrogen potential becomes 0.16 ~ 0.25, and the nitrogen potential becomes 0.16 ~ 0.25. In the atmosphere, keep for 2 to 4 hours, and air-cool to room temperature.

Example 3:

The invention provides a strong and tough hot work die steel, wherein the main materials used in the die steel include the following raw materials by weight: carbon C: 0.20-0.30%, silicon Si: 0.20-0.40%, manganese Mn: 0.40-0.6 %, Molybdenum Mo: 1.50～2.20%, Nickel Ni: 0.50～0.80%, Niobium Nb: 0.50～0.60%, Cobalt Co: 0.50～0.60%, Chromium Cr: 5.00～5.40%, Yttrium Y: 0.01～0.03%, Vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities sulfur S≤0.006%, phosphorus P≤0.018%.

Specifically in this embodiment, the main materials used in the die steel include the following raw materials by weight: carbon C0.30%, silicon Si: 0.40%, manganese Mn: 0.6%, molybdenum Mo: 2.20%, nickel Ni: 0.80%, Niobium Nb: 0.60%, Cobalt Co: 0.60%, Chromium Cr: 5.40%, Yttrium Y: 0.03%, Vanadium V: 0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities Sulfur S≤0.006%, phosphorus P≤0.01%.

The invention provides a production method of strong and tough hot work die steel, comprising the following operation steps:

S1. Smelting and filtration: heating the raw materials to above 1500°C in a smelting furnace and smelting into molten steel, pouring the prepared molten steel into a filtration furnace to remove excess phosphorus, sulfur and other impurities;

S2, vacuum treatment: inert gas is sprayed into the reduction furnace, and the molten material can be stirred during the blowing process;

S3. High temperature homogenization: heat the cooled steel billet to 1100°C, and after holding for a predetermined time, cool to 150°C for the first homogenization to obtain a primary homogeneous steel ingot, and heat it again to 1260°C-1300°C for homogenization. Quality 5 to 8 hours;

S4. Forging: The three-pier three-pulling deformation process is used to forge the steel billet in three directions of X-axis, Y-axis, Z-axis, and the initial forging temperature is set at 1100 ° C ~ 1150 ° C, and the final forging temperature is 900 ° C. After heating, keep warm 1-2 hours to take out forging, when the temperature drops to 900 ℃, return to the furnace to heat to the initial forging temperature and then cycle forging again;

S5. Staged heat treatment:

In the first stage, the forging after high temperature diffusion is heated to 500°C to 650°C at a heating rate of 10°C to 15°C/min, kept for 1 to 2 hours, and then water-cooled to room temperature;

In the second stage, the forging after high temperature diffusion is raised to 850°C to 880°C at a heating rate of 7°C to 12°C/min, kept for 2 to 3 hours, and then water-cooled to room temperature;

In the third stage, the forgings after high temperature diffusion are heated to 1020°C to 1050°C three times at a heating rate of 5°C to 8°C/min, and kept for 20-25 hours;

S6. Staged cold treatment:

In the pre-cooling stage, pressurize the furnace so that the pressure value is maintained at 5-8 bar, and cool the heat-treated forgings to 820-900 ℃ with the furnace, and keep the temperature for 2 hours;

In the initial cooling stage, the heat-treated forgings are cooled to 400-450 ℃ with the furnace, the pressure in the furnace is released, and after holding for 2 hours, air-cooled to room temperature;

In the cryogenic stage, the heat-treated forgings are cooled to -120 to -90 °C, maintained for 2 hours, and then air-cooled to room temperature;

S7, nitriding treatment:

In the initial nitriding treatment, the cold-treated forgings are heated to 800 ℃ ~ 900 ℃ with the furnace, and the gas in the furnace is formed convection through the stirring device. Carry out in gas atmosphere, and introduce unsaturated hydrocarbon gas and ammonia gas at the same time;

In the second nitriding treatment, in the second nitriding treatment process, the temperature in the furnace is lowered to 500 ° C ~ 600 ° C, and ammonia gas and hydrogen gas are introduced into the heating chamber, so that the nitrogen potential becomes 0.16 ~ 0.25, and the nitrogen potential becomes 0.16 ~ 0.25. In the atmosphere, keep for 2 to 4 hours, and air-cool to room temperature.

Example 4:

Get the hot work die steel prepared by above-mentioned embodiment 1-3 respectively and test, obtain the following data:

It can be seen from the above table that the proportion of raw materials in Example 2 is moderate, and the die steel prepared by cooperating with its production process has good toughness, ductility and stability, and the nano-strengthening of the internal distribution is relatively uniform, thereby improving Its high temperature resistance and corrosion resistance.

Finally: the above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the present invention. within the scope of protection.

Claims (8)

1. A strong and tough hot work die steel, characterized in that: the main material used in the die steel comprises the following raw materials by weight: carbon C: 0.20～0.30%, silicon Si: 0.20～0.40%, manganese Mn: 0.40 ～0.6%, Molybdenum Mo: 1.50～2.20%, Nickel Ni: 0.50～0.80%, Niobium Nb: 0.50～0.60%, Cobalt Co: 0.50～0.60%, Chromium Cr: 5.00～5.40%, Yttrium Y: 0.01～0.03 %, vanadium V: 0.50～0.60%, O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities sulfur S≤0.006%, phosphorus P≤0.018%. 2. a kind of production method that is used for a kind of toughness hot work die steel described in claim 1, is characterized in that: comprise the following operation steps: S1. Smelting and filtration: heating the raw materials to above 1500°C in a smelting furnace and smelting into molten steel, pouring the prepared molten steel into a filtration furnace to remove excess phosphorus, sulfur and other impurities; S2, vacuum treatment: inert gas is sprayed into the reduction furnace, and the molten material can be stirred during the blowing process; S3. High temperature homogenization: heat the cooled steel billet to 1100°C, and after holding for a predetermined time, cool to 150°C for the first homogenization to obtain a primary homogeneous steel ingot, and heat it again to 1260°C-1300°C for homogenization. Quality 5 to 8 hours; S4. Forging: The three-pier three-pulling deformation process is used to forge the steel billet in three directions of X-axis, Y-axis, Z-axis, and the initial forging temperature is set at 1100 ° C ~ 1150 ° C, and the final forging temperature is 900 ° C. After heating, keep warm 1-2 hours to take out forging, when the temperature drops to 900 ℃, return to the furnace to heat to the initial forging temperature and then cycle forging again; S5. Staged heat treatment: In the first stage, the forging after high temperature diffusion is heated to 500°C to 650°C at a heating rate of 10°C to 15°C/min, kept for 1 to 2 hours, and then water-cooled to room temperature; In the second stage, the forging after high temperature diffusion is raised to 850°C to 880°C at a heating rate of 7°C to 12°C/min, kept for 2 to 3 hours, and then water-cooled to room temperature; In the third stage, the forgings after high temperature diffusion are heated to 1020°C to 1050°C three times at a heating rate of 5°C to 8°C/min, and kept for 20-25 hours; S6. Staged cold treatment: In the pre-cooling stage, pressurize the furnace so that the pressure value is maintained at 5-8 bar, and cool the heat-treated forgings to 820-900 ℃ with the furnace, and keep the temperature for 2 hours; In the initial cooling stage, the heat-treated forgings are cooled to 400-450 ℃ with the furnace, the pressure in the furnace is released, and after holding for 2 hours, air-cooled to room temperature; In the cryogenic stage, the heat-treated forgings are cooled to -120 to -90 °C, maintained for 2 hours, and then air-cooled to room temperature; S7, nitriding treatment: In the initial nitriding treatment, the cold-treated forgings are heated to 800 ℃ ~ 900 ℃ with the furnace, and the gas in the furnace is formed convection through the stirring device. Carry out in gas atmosphere, and introduce unsaturated hydrocarbon gas and ammonia gas at the same time; In the second nitriding treatment, in the second nitriding treatment process, the temperature in the furnace is lowered to 500 ° C ~ 600 ° C, and ammonia gas and hydrogen gas are introduced into the heating chamber, so that the nitrogen potential becomes 0.16 ~ 0.25, and the nitrogen potential becomes 0.16 ~ 0.25. In the atmosphere, keep for 2 to 4 hours, and air-cool to room temperature. 3. the production method of a kind of strong toughness hot work die steel according to claim 2, it is characterized in that: in described step S3, the billet is heated to 1100 ℃, after heat preservation predetermined time, in the step of cooling to 175 ℃ , when the effective thickness of the steel billet is greater than 350 mm, the cooling rate is: 8-10°C/min; when the effective thickness of the steel billet is less than 350 mm, the cooling rate is: 10 -20°C/min. 4. the production method of a kind of strong toughness hot work die steel according to claim 2, it is characterized in that: in described step S5 in the staged heat treatment process, water cooling to room temperature can choose oil cooling to room temperature or air cooling to room temperature. 5. the production method of a kind of strong toughness hot work die steel according to claim 2, is characterized in that: in described step S6, the interval time of described importing unsaturated hydrocarbon gas and ammonia gas intermittently is 2min ~6min, the flow rate of unsaturated hydrocarbon gas and ammonia gas is (0.35 ~ 0.65) m3/h each time. 6. The method for producing a strong and tough hot work die steel according to claim 1, wherein the used main material comprises the following raw materials by weight: carbon C: 0.20%, silicon Si: 0.20% , manganese Mn: 0.45%, molybdenum Mo: 2.00%, nickel Ni: 0.50%, niobium Nb: 0.55%, cobalt Co: 0.50%, chromium Cr: 5.00%, yttrium Y: 0.01%, vanadium V: 0.50 ~ 0.60% , O≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities sulfur S≤0.006%, phosphorus P≤0.01%. 7. The production method of a strong and tough hot work die steel according to claim 1, wherein the used main material comprises the following raw materials by weight: carbon C: 0.25%, silicon Si: 0.30% , Manganese Mn: 0.50%, Mo Mo: 1.90%, Nickel Ni: 0.65%, Niobium Nb: 0.55%, Cobalt Co: 0.55%, Chromium Cr: 5.20%, Yttrium Y: 0.023%, Vanadium V: 0.55%, O ≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities, sulfur S≤0.006%, phosphorus P≤0.01%. 8. The method for producing a strong and tough hot work die steel according to claim 1, wherein the used main material comprises the following raw materials by weight: carbon C 0.30%, silicon Si: 0.40% , Manganese Mn: 0.6%, Molybdenum Mo: 2.20%, Nickel Ni: 0.80%, Niobium Nb: 0.60%, Cobalt Co: 0.60%, Chromium Cr: 5.40%, Yttrium Y: 0.03%, Vanadium V: 0.60%, O ≤25ppm, N≤40ppm, the rest are Fe and inevitable impurities, sulfur S≤0.006%, phosphorus P≤0.01%.